Yes he was a sorcerer in life and according to Tolkien the wraiths retained the abilities they had in life and I say as much in my first post. Also the WKing demonstrates some sort of spell againsr Frodo at Brunien as well as assisting Grond in breaking the doors at the Seige of Gondor but he never exhibits any "enhanced power" as people are putting it in any of his physical battles otherwise he would have used it instead of attacking people with his fell beast and his mace. The disinction I am trying to make is that people should not confuse the apparent nature of his increase in power that he exhibits in the movie with what Tolkien had intended when commenting on "demonic force". The increase in his ability to cause fear which is repeatedly explained in the books and supporting sources as their primary weapon was enough in itself to have a massive effect at Pelennor but nothing else is ever shown apart from the breaking of the gate, vso I would be interested in any proof you have that you think explains why he would have had an added advantage in combat against Gandalf at Pelennor as opposed to Aragorn at Weathertop.